Cockroaches are disgusting to many people. They are widespread all over the world and extremely resilient. They prefer human dwellings. The following article will help you to identify cockroaches, eggs and larvae.

In a nutshell

  • Cockroaches prefer dark, warm and humid places
  • Cockroach is a notorious storage pest
  • Body length up to 30 mm
  • Color brown-black
  • Eggs are laid in egg packets

Recognizing cockroaches correctly

The common cockroach (Blatta orientalis) is also known under the names cockroaches, baker's cockroach or oriental cockroach. The animals are extremely light-shy and therefore active at dusk and at night. They are considered omnivores. They mainly soil food with their droppings. At first glance, a cockroach can be mistaken for a beetle. However, it is possible to identify a cockroach without a doubt based on the following characteristics:

Heinonlein, Blatta orientalis, Isalo 01, crop from Plantopedia, CC BY-SA 4.0
  • Body length males up to 25 mm
  • Body length females up to 30 mm
  • Body flat and slightly rounded to oval
  • dark brown to black colored chitin shell
  • Males are slightly lighter colored than females
  • 6 long, spiky legs
  • light brown leg color
  • small claws at the ends of the legs
  • 2 long, thin antennae on the head
  • are a third as long as the body
  • transparent neck shield
  • wings rudimentarily reduced in females
  • in males, wings cover three quarters of the abdomen

Even if the males have wings, a cockroach cannot fly because it is a bit heavy. In return, the animals move extremely quickly on the ground. Here they can reach speeds of up to 5 km/h. Cockroaches live in large colonies and their nests are well camouflaged.

Notice: The animals can be found in dark, humid and warm places with prevailing temperatures between 20 and 29°C. Places in the kitchen, bathroom, boiler room or laundry room are ideal.

Oviposition in oothecae

Cockroaches can multiply rapidly. They belong to the oviparous species, which means that they reproduce by laying eggs. Mating females lay their eggs at intervals of several days in five to ten egg packets, so-called oothecae, in warm, humid and sheltered places. These are very resilient and such an egg pack contains 16 eggs each. The female cockroaches carry the eggs on their abdomen for about two days before they are laid. Only after they have been filed are they able to live on their own. Ootheca are:

The common cockroach filing an ootheca; Source: gailhampshire from Cradley, Malvern, UK, Common Cockroach giving birth. Blatta orientalis. - Flickr - gailhampshire, edited by Plantopedia, CC BY 2.0
  • up to 12 mm long
  • smooth-walled, dark brown in color
  • surrounded by a hard protective shell containing chitin

The protective cover is thick and waterproof. It protects the eggs from weather-related influences such as moisture or strong temperature fluctuations and also from predators such as spiders. Furthermore, there is a keel, a kind of seam, on the long side of an egg packet. These open the larvae of the cockroaches when they hatch. Under favorable living conditions, the adult females can live up to 150 days and lay up to 20 such oothecae during this time. However, it takes a few months for the larvae to fully mature.

Notice: Cockroaches can survive up to nine days without a head. This is possible because there is only a small part of the nervous system in the head. The brain itself is in the body. Without a head, it is more likely to have problems eating and drinking.

Hatch as nymphs

An egg takes 1.5 to 2 months to develop before the larvae hatch in the form of nymphs. The term nymph is used here for cockroaches because they do not have their own larval characteristics like larvae normally have. The hatched nymphs already resemble the adult animals, the imagines, in their appearance. Only they are smaller and are not yet sexually mature. Depending on the prevailing temperature, the nymphs need 125 days in the best case and up to 540 days in the worst case to develop into adult animals. Since cockroaches belong to hemimetabolous insects, further development occurs in different stages. Each stage that the larvae of the cockroach go through ends with a moult. In summary:

skinning of a nymph; Source: Ildar Sagdejev (Specious), 2004-11-07 Blatta orientalis ecdysis, edited by Plantopedia, CC BY-SA 3.0
  • Nymphs normally go through up to 5 larval instars
  • accordingly five moults
  • Remnants of skin transparent
  • freshly skinned animals are light colored
  • new tank needs at least 6 hours to harden
  • under unfavorable conditions up to 10 molts possible
  • from the 3rd larval stage light brown coloration occurs
  • from the 4th larval stage only dark brown to black discoloration
  • with the last molt direct development to the adult cockroach

Notice: Controlling cockroaches is not exactly easy. They are very resilient. The control measures can last for months and must be repeated regularly.

frequently asked Questions

Are cockroaches dangerous to humans?

These animals are primarily feared as storage pests. They contaminate a wide variety of foods with their droppings. They are also considered potential disease vectors. Not only Salmonella, but also pathogens of anthrax, tuberculosis, dysentery, polio and also typhus, cholera or hepatitis can be transmitted.

How can a cockroach infestation in the apartment be recognized?

There are different ways. In addition to transparent moulting residues of the larvae, one centimeter large, brown egg packets near hiding places can indicate this. In addition, 0.5 mm large brown excretions along the walls, signs of eating on food and packaging, and a penetrating, sweet smell also indicate cockroaches.

How can a cockroach infestation be prevented in the home?

Order and cleanliness is of course the top priority. No leftovers should be left unattended, rubbish bins must be tightly closed, food should be stored in transparent containers that can be closed easily. In addition, regular ventilation is necessary, as well as thorough cleaning of the rooms behind and under cupboards, etc. Not to be forgotten is the sealing of cracks and holes in the masonry and floors.

Category:

Garden pests